Concentrated aqueous solutions of the ammonium salts of disubstituted dithiophosphoric acids



Patented Jul z, 1940 PATENT OFFICE CONCENTBATED AQUEOUS SOLUTIONS OF THE AMLIONIUM SALTS F DISUBSTI- TUTED DITHIOPHOSPHORIC ACIDS David W. Jayne, Jr., Old Greenwich, Conn, as-

signor to American Cyanamid Company, New

York, N. Y., a corporation of Maine Application October #1, 1939, Serial No. 309,582

No Drawing.

1 Claims. (01. zszs) The present invention relates to promoters for use in the froth flotation and mineral separation of sulflde ores and the like. More particularly it relates to concentrated aqueous solutions of the 5 ammonium salts ofdisubstituted dithiophosphoric acids and methods of preparation.

The dialkyl and/or dlaryl -dithiophosphoric acids have been used on a large scale for the flotation of various sulflde and precious metal ores for which they have been found to be very eflfective promoters. While these dlthiophosphoric acid derivatives are excellent promoters there are, however, certain undesirable factors.

, which accompany their use. For example, they are only slightly soluble in water and certain-of the dialkyl dlthiophosphoric acids are very corrosive and therefore require special containers and precaution in transportation, storage, handling, etc. Also water has a endency to cause rather rapid decomposition of the disubstituted cient as promoters and hence somewhat limits their use, particularly where it is desired to feed the reagent in the form of aqueous solutions, which presents important advantages.

To overcome the objectionable features of the disubstituted dithiophosphoric acids it has been proposed to use various salts of these acids, among which are the ammonium salts. There are, however, some undesirable properties possessed by certain of the ammonium salts which have not been satisfactorily solved heretofore. The ammonium salts of these di-substituted dithiophosphoric acids are diflicult to prepare in the anhydrous form and usually occur in the form of either solids, pastes, or rather stiii jellies which are relatively unstable. These ammonium salts in the form of solids or pastes are not only diflicult to prepare, but are diflicult to handle and to dissolve, disperse or dilute with water when it is desired to feed themn'nto a flotation.

dithlophosphoric acids to render them less em as is practical (i. e., 28-30% m) in order that the product will contain a maximum and relaphoric acids can be prepared in a concentrated aqueous solution of uniform strength suitable for use, as a flotation reagent,and that the stability of such solutions is insured by maintaining an excess of ammonia. The excess ammonia, while 5 it prevents the presence of any free disubstituted dithiophosphoric acids which would be hydrolyzed in the presence of water, does not interfere with the use of such solutions as flotationreagents.

In the preferred method of carrying out this 10 invention disubstituteddithiophosphoric acids, such as diaryl dithiophosphoric acids or dialkyl dithiophosphoric acids are added to aqua ammonia (i. e., ammonium hydroxide containing 28-30% Nl-l'a) in quantities that will leave an excess of ammonium hydroxide after neutralizing 15 the acid, to give a stable concentrated aqueous solution of the ammonium salt. The concentrated aqueous solution so produced may be dissolved in water to give more dilute solutions which can be readily fed to an ore flotation circuit when such products are used as ore flotation tively uniform quantity of active ingredient. While the ammonium hydroxide solution employed preferably contains 28 to 30% NH: weaker 35 solutions may be used' and solutions containing only about 25% NH: have been found to produce satisfactory results. 'The disubs'tituted dithiophosphoric acids used need not be amolutely pure but may be used in the crude form having im- 40 in connection with other promoters or collectors, to

trothers or the like, for example, the addition of a small amount of thiocarbanilid in many instances produces improved flotation results. The invention will'be further illustrated by the following examples which are included for purposes 01 illustration and the invention is not limited thereto.

Example 1 100 grams of 26 B. aqua ammonia were placed in a 3 neck flask surrounded by acooling bath and fitted with a mechanical agitator, thdrmometer and dropping funnel. 500 grams of a crude mixture of approximately 80% diaryl dithiophosphoric acids (cresyl, xylenyl, etc.) and of free cresylic acid" were placed in the dropping funnel. The crude acid was added to Example 2 are limited to and include only such radicals when they are hydrocarbons.

quired to neutralize the acid.

What I claim is: V

1. A composition of matter comprising a stable, concentrated, aqueous solution of the ammonium salts of at least one of the compounds included in the group consisting of dialkyl and diaryl dithiophosphoric acids, said solution containing an amount of ammonium hydroxide in excess of the amount required to neutralize the acid.

2. A stable, concentrated, aqueous solution of the ammonium salt of a dialkyl dithiophosphoric acid, said solution containing an amount of ammonium hydroxide in excess of the amount rethereby leaving a slight excess of ammonium hydroxide.

50 g. of 26 36. aqua ammonia were placed in a 3 neck flask fitted with a mechanical agitator, thermometer and dropping funnel and surrounded by a cooling bath. 200 g. of crude di-secondary amyl dithiophosphoric acid were placed in the dropping funnel and the acid added to the aqua ammonia, with agitation, at such a rate that the temperature of the batch was maintained between and 30 C. The product (aqueous ammonium salt of di-secondary amyl dithiophosphoric acid) was a clear dark yellowgreen, homogeneous liquid, containing about 18% water. The product readily dissolved in water to give a somewhat cloudy, dilute, alkaline soluq tion.

The term alkyl and aryl* used in the claims 5. -A method of preparing stable, concentrated, aqueous solutions or the ammonium salts of diaryl dithiophosphoric acids which comprise adding diaryl dithiophosphoric acids to ammonium hydroxide containing about 28% NH: in quantities insuflicient to neutralize the ammonia, thereby leaving a slight excess of ammonium hydroxide.

6. A stable, concentrated, aqueous solution of the ammonium salt of dicresyl dithiophosphoric acid, said solution containing an amount of am: monium hydroxide in excess of the amount required to neutralize the acid.

7. A stable, concentrated, aqueous solution of the ammonium salt of di-secondary amyl dithiophosphoric acid, said solution containing an amount ofammonium hydroxide in excess of the amount required to neutralize the acid.

' DAVID W. JAYNE, JR. 

